文献类型：期刊文献

英文题名：Preventing oxide precipitation in selective wet etching of Si3N4 for 3D-NAND structure fabrication: The role of bubbles

作者：Zhang, Hao[1];Yang, Haiqiang[1];Yuan, Fang[1];Liu, Bo[1];Yang, Qiang[1]

机构：[1]East China Univ Sci & Technol, Dept Mech & Power Engn, 130 Meilong Rd,Lingyunlu St, Shanghai, Peoples R China

年份：2024

卷号：283

外文期刊名：MICROELECTRONIC ENGINEERING

收录：;EI(收录号：20234414993612);Scopus(收录号：2-s2.0-85175148896);WOS:【SCI-EXPANDED(收录号:WOS:001103981800001)】；

基金：This work was financially supported by the National Natural Science Foundation of China (Nos. 22178099) , the Open Project of State Key Laboratory of Chemical Engineering (SKL-ChE-22C02) , the Shanghai Natural Science Foundation (21ZR1417000) , the Shanghai Pujiang Program (21PJ1402000) , and the Special Project for Peak Carbon Di- oxide Emissions -Carbon Neutrality (21DZ1207800) from the Shanghai Municipal Science and Technology Commission.

语种：英文

外文关键词：Silicon nitride; 3D NAND; Etching; Precipitation; CO 2 gas

摘要：Selective wet etching of Si3N4 is a critical process in the fabrication of 3D-NAND structures; however, it faces a oxide precipitation problem that significantly deteriorates the remaining structure morphology. A recent study by Kim et al.(Kim et al., 2022 [1]) showed that generating CO2 bubbles during the wet etching process efficiently solves the precipitation problem in the fabrication of a 128 multi-layer 3D-NAND structure. In this study, we numerically investigated the multiscale diffusive transport of oxides in the etching process via three different simplified simulations at different scales to reveal the underlying mechanism. We found that mass transport within the multilayer structures alone cannot contribute to the oxide precipitation behavior. Macroscopic transport from the wafer-etchant interface to the bulk must be considered since it contributes to a high oxide concentration at the wafer-etchant surface, which further increases the concentration within the trenches, leading to the precipitation problem. Through the conjecture oxide transport simulation, we found that the large bubbles generated from the reaction agitate the surrounding liquid and dramatically reduce the oxide concen-tration at the wafer-etchant surface by one order of magnitude, thereby solving the precipitation problem. Our findings clearly explain the experimental results reported by Kim et al. and will further benefit the development of process-intensification technologies in wet etching.